PROXIMAL RENAL TUBULE PREPARATIONS ISOLATED FROM RAT OR RABBIT KIDNEYS WITHOUT THE USE OF COLLAGENASE

Kidney tubules have previously been isolated from a number of differen t animal species using techniques involving perfusion and digestion of the organ with collagenase, followed by centrifugation of the resulti ng suspension. These techniques suffer from the disadvantages of requi ring prolonged incubation with a potentially damaging enzyme and conta mination of the preparations with glomeruli. We have developed a proce dure for the isolation of a purified preparation of rabbit kidney tubu les without collagenase digestion. Rabbit or rat kidneys are perfused with buffer, followed by a suspension of magnetic iron oxide. The cort ex is then homogenized by hand and put through nylon sieves of varying mesh sizes that separate large pieces of tissue from the glomeruli an d tubules, which are caught on the smaller mesh sieves. The glomeruli containing entrapped iron oxide are then separated from the tubules wi th the aid of a magnet. Tubules isolated in this way are morphological ly intact as shown by electron microscopy and have intact basement mem branes in contrast to those isolated with the use of collagenase treat ment. These tubules are equal to or surpass those isolated with the us e of collagenase in metabolic functions such as oxidative metabolism a nd gluconeogenesis and in transport functions such as PAH and 2-deoxyg lucose uptake.